1. Field of the Invention
The present invention relates generally to interlocked zooming apparatuses suitable for use in a stereo camera comprising a pair of video cameras, or the like, and more particularly to an interlocked zooming apparatus capable of easily carrying out interlocked zooming.
2. Description of the Background Art
An interlocked zooming apparatus of interest in regard to the present invention is disclosed in, for example, Japanese Patent Laying-Open Gazette No. 62687/1982. FIG. 1 is a typical diagram showing an image pick up apparatus comprising a conventional interlocked zooming apparatus, as appearing above-noted in the gazette.
Referring to FIG. 1, the image pick up apparatus having the conventional interlocked zooming apparatus comprises first and second video cameras 101 and 102 for sensing an image of an object 116 to be photographed, a synchronizing signal generator 117 for generating a signal for operating the first and second video cameras 101 and 102 in a synchronized manner, and a signal switching device 118 for switching output signals from the first and second video cameras 101 and 102. The first and second video cameras 101 and 102 respectively comprise first and second zoom lenses 103 and 104 for zooming. The first and second zoom lenses 103 and 104 respectively comprise variator means 105 and 106 for varying the magnification of the object by respectively changing the focal lengths of the zoom lenses, and focusing means 108 and 109 for respectively adjusting the focuses of the zoom lenses changed by the variator means 105 and 106. The conventional interlocked zooming apparatus further comprises an in-focus operating member 107 for interlocking the focusing means 108 and 109 with each other and a variator operating member 110 for interlocking the variator means 105 and 106 with each other. Both the in-focus operating member 107 and the variator operating member 110 are operated by manually operating portions 41 and 44. Connections between the focusing means 108 and 109 and the in-focus operating member 107 and between the variator means 105 and 106 and the variator operating member 110 are respectively made by flexible cables 111.
Description is now made of an operation of the conventional interlocked zooming apparatus. When the first and second video cameras 101 and 102 are interlocked with each other for zooming, a user manually operates the manually operating portions 41 and 44 of the variator operating member 110 and the in-focus operating member 107 while watching a monitor screen (not shown) for two video cameras. Consequently, the first and second video cameras 101 and 102 are manually adjusted such that images at the time of zooming match.
The conventional interlocked zooming apparatus is structured as described above. Thus, the zoom lenses of the right and left video cameras must be manually adjusted every time the condition for sensing an image, such as a place where a picture is taken, is changed. Thus, the operability of the cameras is poor at the time of sensing an image, so that it takes an extended period of time to take a picture.
Additionally, in the conventional interlocked zooming apparatus, the range of adjustment of two zoom lenses is limited. More specifically, the first and second zoom lenses are not necessarily manufactured to be all the same. Even through the first and second zoom lenses are manufactured to be all the same, they are not necessarily incorporated in the main bodies of the video cameras in the same manner. Various parts used when the zoom lenses are respectively incorporated in the video cameras are not all the same. Since an ordinary DC motor is used as a motor for moving the zoom lenses via electric power, it is difficult to uniformly perform the control. In addition, it is difficult to make constant the environmental condition at the time of sensing an image and setting of the pair of cameras. Thus, it is difficult for a user to manually adjust the sizes of images formed by a pair of video cameras under such conditions. More specifically, it is actually difficult to simultaneously adjust the sizes of the right and left images according to changes in zoom ratios of the zoom lenses by manually operating the focusing means and the variator means in a two-barrel type stereo scopic camera.